Compression ignition gun



Aug. 2, 1960 D. u. GRIFFIN ETAL COMPRESSION IGNITION GUN 3 Sheets-Sheet 1 Filed Dec. 10, 1956 k v nu TN Q v \N INVENTORS DONALD N.GRIFFIN JOHN w. ORR

Aug. 2, 1960 Filed Dec. 10, 1956 D. N. GRIFFIN ETAL COMPRESSION IGNITION GUN 3 Sheets-Sheet 2 INVENTORS DONALD N. GRIFFIN JOHN W. ORR

D. N. GRIFFIN ETAL 2,947,221

Aug. 2, 1960 COMPRESSION IGNITION GUN Filed Dec. 10, 1956 3 Sheets-Sheet 3 IN V EN TORS DONALD N. GRIFFIN JOHN W. ORR

COMPRESSION IGNITION GUN Donald N. Griflin, Niagara Falls, N.Y., and John W. Orr, Duarte, Califi, assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia Filed Dec. 10, 1956, Ser. No. 627,724

2 Claims. (Cl. 89-7) The present invention relates to devices for advancing projectiles and is particularly concerned with projectile advancing devices which utilize fluid monopropellants.

Our invention, in particular, utilizes the phenomenon of vapor compression ignition to ignite and explode a charge of liquid propellant in a firing or compression chamber to propel a projectile from the chamber.

Vapor phase ignition of combustible substances by adiabatic compression is a well-known phenomenon and has heretofore been utilized on a large scale for ignition of air-fuel mixtures in diesel engines and the like. The compression ignition phenomenon has also been found to be undesirable and even hazardous in other circumstances, for example, in the use of liquid monopropellants in various rocket applications where the monopropellant can be subjected to sudden compression when vaporized or partially vaporized duringrapid opening or closing of valves in the pumping system.

It is a particular object of the present invention to provide a projectile propulsion mechanism in which the phenomenon of compression ignition is utilized.

It is a further object of the present invention to provide a purely mechanical ignition system for such a mechanism, thus eliminating the need for fixed ammunition, primers, electric sparks or other ignition schemes.

A still further object of the invention is the provision of an automatic weapon of any desired caliber wherein the propellant in liquid form may be contained conveniently in a reservoir attached to or closely associated with the weapon.

Another object of the invention is the provision of a gun in which the projectiles or bullets are handled separately and are thus not associated with a cartridge casing of any kind.

Another object of the invention is the provision of a compression ignition liquid propellant projectile advancing scheme which is readily adaptable to present day powder actuated tools. The tools referred to here are those used to drive rivets, bolts, studs, and other fasteners.

Basically, the propulsion mechanism of the present invention simply requires a main body member of any desired shape formed with a bore defining a cylinder, a barrel having a firing chamber and adapted to receive a projectile therein, said barrel being removably attached to and communicating with the bore of the cylinder, a piston slidably positioned within the bore, projecting into the firing chamber and provided with a mechanism such as a spring for driving the piston forward towards the mouth of the barrel to reduce the volume of the firing chamber.

The mechanism is operated by chambering a bullet, a stud or other projectile at the forward end ofthe chamber, ramming the projectile home (usually to the beginning of the rifling or other sealing means) and injecting a metered charge of a liquid propellant, susceptible of compression ignition, into the chamber between the pis-.

ton and the projectile. Thus, the propellant is connited States Fatenr ready for the next compression stroke.

'ceptible of compression ignition. V -monopropellants are nitro-methane, propyl nitrate, and

tained within a cavity of the firing chamber bounded on the forward end by the projectile (which makes a fluid tight seal with the barrel) and rearwardlybythe piston;

As will become more apparent hereinafter, the bullet may be inserted by hand through the rear end of the chamber by providing a suitable quick operating disconnector between the barrel and the cylinder or by providing a slidable bolt as in a bolt action firearm.

After the bullet and the liquid propellant are positioned as described above, the piston is driven forward towards the projectile causing the gasesor vapor in the chamber to be compressed under approximately adiabatic conditions. The internal heat generated thereby ignites and explodes the propellant, driving the bullet,

- stud, or other projectile through the barrel and out of the muzzle at high velocity. The reaction of the explosion may be utilized, if desired, to operated upon the piston in the mannerof a blow back operated gun to drive the piston rearwardly where it may be latched The gases or 'vapor's' which are heated by compression in the chamber 'may be air, propellant vapor, or the gaseous products of previous combustionsof the propellant.

It is to be understood that by the term propellan it is intended to designate liquid monopropellants sus- Examples of such a mixture containing by weight approximately ,60percent hydrazine, approximately 33 percent hydrazine nitrate and about 7 percent water.

It is to be noted that propellants of the above-general be described. The invention will also be described as adaptedto a conventional single shot rifle.

Obviously, the principles of the invention are nOt limited to firearms but are adaptable to so-called powder actuated tools utilized to drive studs or bolts intobuilding materials. Accordingly, the use of the term projecti1e herein is intended to include bullets, studs, bolts, rivets and the like.

'Referring now to Fig. 1, there is shown schematically a sectional view of a firing mechanism constructed in accordance with the principles of the present invention and illustrating to advantage a projectile seated in the firing or compression chamber, the piston in the cocked position and propellant being injected into the firing chamber;

Fig. 2 is a view similar to Fig.1 and shows the piston advancing toward the projectile to bring about adiabatic compression of the monopropellant;

Fig. 3 is also similar to Fig. 1 and shows the projectile leaving the barrel and the piston at a point along its return path; Y f

Fig. 4 shows the piston fully returned and latched readyfor the next firing;

Fig. 5 is 'an elevational view of a portion of a single shot rifle with which the principles of the invention may be associated and showing the compression piston in the forwardposition;

Fig. 6 is a view similar to the showing of Fig. 5 illustrating the compression piston in the rear or cocked position; g

Fig. 7 is a plan view of a portion of the showing the bolt operating arm to advantage;

Fig. 8 is a view of the sear and bolt assembly, some what enlarged,-in the cocked condition;

Fig. 9 is a view of the same elements in the position which represents'the start of the pump stroke; and

Fig. 10 :is a view of the .clements in the position which iIFPIQSeXItst-he end oflthe pump stroke.

.Referripgmowlofiga. 1. through .4, the reference .numetal 20.designates.. a barrellhavinga rifled bore 21'termin'ating in a smooth bore defining a firing char'nber..22.

-A; piston.23.having ahead. 241s. slidably, positioned in ...the chamber. .The rear. end of the.barrel. 20,is received within and removably. fastened,.by.means not shown, to a. cylinder or tubular spring case 26. It is intended that the barrel. wand the cylinder: 26 thIeadedly-engageone another, such as. by interrupted threads so that the barrel =.may. be readily. :removed, for .thepurpose of insertipgua projectile.25.into the chamberand ramming it. home (to theoriginof the rifting) .to make a fluid .tight seal. As .shewn in. the drawings, the. cylinder 26 is ,enclosedby a .plate 27 and the pistonhead '24 is. slidable in the cylin- :LlCl'. Disposed betweenthepiston head and theplate is ,a coil spring 28. The springis under a substantial compressiye. load at. all times and is used to drive the, piston toward=the projectile.

:The compression orfiring chamber 22 is providedwith a port 29 through .whicha metered charge of fluid mono- ,,prppellant.of.the type previously described is injected between the. piston :23..:and .the projectile 25 disposed as shown ,in Fig. 1.

The port 29 must be fitted with a one way check valve whichopposes discharge offluid from the interior of the chamberandapy suitable positive displacement pump .smeans.may..be..utilized tov meter the liquid through the :barrelinto therhamber. When the barrel. 20 and .the cylinder..26,aredisconnected forthe purpose of inserting .a projectile, the piston 23 is pushed rearwardly compressing the spring 28. A latch31 is provided for latch- ..ingtheheadof the piston in the position shown in Fig. 1.

..Since .ignition .of theliquid propellant is accomplished ;.by. adiabatic compression, aminimum compression ratio is required: to;generate suflicient heat to cause ignition. -Thisuminimum -compression ratio is dependent on the ,:particulanpropellantused,rand also on the ratio of liquid to;.y apor. volume in the chamber. Compression ratio is controlled by theqforce of the spring, and the mass and cross-sectional area of the piston, and compression ratios ashigh as; 100:1 are sometimes required.

twiththe piston latched by the element 31v andpropel- ...lant..-disposed between the head of the piston and the bullet 2.5 as shown in Fig. 1, release of the'piston will permit it to drive forwardly toward the projectile in re- ..sponse to the urging of the spring28. A sudden and substantially adiabatic compression of the vapor volume ..in.the chamber occurs, generating suificient internal heat to bring about ignition.

.Ijpon ignition, the propellant burns explosively and the projectile or bullet is propelled along the barrel and leaves the barrel at high velocity, as shown in Fig. 3, -while the piston '23 is driven toward the rear in theman- .ner .ot a firearm having blow-backoperation. The

blow-back action of the piston occurs.at.-a relatively low velocity because of its high mass (relative to the mass of the projectile) and the head of the piston overrides the 'latch 31 and is latched in the position shown-in Fig. 4.

--Referring now to Figs. through and in particular to Figs. 5, 6, and 7, there is shown'a shoulderifirearm .with which theprinciples of thepresent invention may ..be-.-utilized. A bolt-action rifle designated. generally by the: reference number :41 is provided with a bolt 42 having an operating handle 43. The bolt-istslidable to and fro, in a slide 44.

Obviously, the bolt mayybe moved from -a forward position as shown in Fig. 7 to a rear or open position as ;represented by the dotted lines in:Fig.-7. :In the open position, projectilesssuchgasra .bUIIEt AGZHIEYZ bC readily ..inserted:,-into= .thezbarrel as. at .45. The bolt ..-is; provided with a first bore47 which communicates with a second 1.4. bore 48 hereinafter referred to as a compression or firing chamber. 'A piston 51 having a head 52 isslidable within the bolt. A coil spring 531is operable to urge the piston to the right as viewed in Fig. 5.

The bolt 42 is of the rotating'lock type and as is apparent in Fig. 7 is operable to be rotated until the operating handle 43 is in alignment with' the slide 44 and may thereafter be movedgtoxandiro:alongithelongitudinal axis of the gun.

Upon moving the bolt to' theleft; as viewedinFig: 5, the piston '51 is carried to the-left until a" shoulder 50 formed on the piston overruns a sear '54. The scar is integral with;a.:trigger assemblygrindicated; generally by the reference numeral 56, pivotally mounted in a receiver by a pin 57. A spring58 constantly urges the trigger assembly in a counterclockwise direction so that whenever the piston is moved to the left, a distance sufficient to permit the s'houlder.50-.to:override. the sear,-the piston .is held in a: cocked POSitiOII'aSrShOWIl in Fig: 6. An.arm 59 formed integralwith thetrigger assembly rides upon and actuates apumpcam 61 which in turn bearsupon a pump. piston 62. The pump cam 61.is rotatable about a'pin.65 through-an arorlimited by the slot 64 and .the follower 63.

In the manner which-will' become more apparenthereinafter the pump cam -is-.= operable by manipulation of thetrigger to moveiromthe/position shown .in Pig. 6 to 5) againsta spring? 67 to pump ametered quantityof .fluid past a check valve 68-.into the .chamber48 byway .ofv a conduit 69. It .-is tobe notedthatpump cavityiis also provided .with.a.Icheck -valve 71 tosealthe cavity during the pumping action.

Referring furtber-to.Fig.:5,.1there is shown. a.;1iquid propellant container 72; having a relativelyrnovable bottom 73. The. bottom :is engaged. by; a, push. 74 whichis in turn urged to .the left by: an actuating. spring 76. The actuating spring is constantlyunder compression :-so that a force is. exertedatallztimes onthe pushrrod which. in turn tends to urge the :movable bottomf73 to:.the left thereby pressurizing. propellant withintthexcontainer.

The fluid pressure under which therpropellant is. maintained is selectedzsozasto :be:s1ightly;in excess of the spring pressure exerted by-the pump check valve 71. "In this way, there is alwaysltheassnrance oftransfer of .liquid propellant from the container 68 to the: pump cavity 66 when the pump:piston.assumes1he positionshown in Fig. 6.

It is to be noted that .the .springpressure .of the check valve 68 must be of suflicient strength touprecludeadmitting liquid propellant. into. the chamber: prematurely,

i.e., prior to the pumping stroke. .Inother wordsrthe spring pressure of. check valve-:68 should bein'iexces's of e that of check valve 71.

Attention is directed to-Lthe'fact that operation of. the pump cam and pump piston must occur prior-tolthe passage of the compression piston by the inletconduit 69. This is accomplished-by :providing suflicienth'eight to the sear54. so.:that; there may be appreciable rotation .of the trigger .andtcorresponding IOiallOIIIOf'ThE pump tially rotated ina clockwise direction and-. theipump cam hasbeen rotated correspondingly ina=counterclockwise .direction.

Fig. shows the condition of the respective elements just at the instant of release of the compression piston and upon completion of the pump cam rotation.

It is to be understood that when the trigger assembly and the pump cam reach the position indicated by the showing of Fig. 10, the chamber 48 has received a predetermined charge of fluid propellant. Further travel of the compression piston adiabatically compresses the vapor or gas volume in the chamber generating sufiicient heat to cause ignition of the propellant. Thereafter, rapid burning occurs and the expansion or" the gaseous products of combustion drives the projectile along the rifling and out of the barrel into the atmosphere.

Operation The operation of the firearm illustrated in Figs. 5 through 10 occurs in the following manner:

Assume that the bolt has been opened in the conventional manner and that a bullet in the form of a lead slug has been inserted into the barrel and rammed to the base of the rifling as shown in Fig. 6. Upon closing and locking the bolt, the compression chamber is sealed, the seal being represented at one end by the projectile seated against the riding and at the other end by the compression piston. Assume further that the compression piston is in the cocked position as shown in Fig. 6 having been so disposed by opening the bolt or by the blow back action of a previous explosion. Since the trigger and sear have been overridden by the bolt and the compression piston, the pump cam will be in the position shown in Fig. 6. correspondingly, the pump piston 62 will be disposed to the left as viewed in Fig. 6 and the propellant under fluid pressure within the container 72 will have forced propellant into the pump cavity. Since the check valve in the conduit leading to the compression chamber dominates the pump check valve, a charge of propellant will be confined in the pump cavity.

Upon manipulation of the trigger in the conventional manner, the sear gradually draws away from the pump piston shoulder 50 and in the first predetermined arc of rotation of the trigger, the pump cam will be actuated to drive the pump piston to the right (Fig. 6) with a force sufiicient to generate pressure which overcomes the check valve 68 permitting the charge of propellant to flow into the compression chamber.

Incidentally, attention is directed to the fact that the motivating power for actuating the pump piston need not be derived entirely from manual operation of the trigger. It is to be noted that the compression spring 53 is constantly urging the compression piston to the right. By virtue of the camming action between the shoulder 50 and the sear 54, the spring 53 helps to drive the trigger through its initial arc of rotation.

Continued rotation of the trigger frees the compression piston to move to the right sealing off the inlet port 69 and compressing the charge of propellant to the relatively small volume such as shown in Fig. 5.

The compression ratio of the compression chamber is plished byrepeating the steps just described.

It is to be understood that it is entirely within the scope of the present invention that the principles thereof be'utilized to actuate tools for'advancing rivets, nails,

bolts, etc. into building materials as 'well' to advancing projectiles from firearms.

It is' also within the contemplation of the invention that the principles thereof be utilized in automatic firearms in which the blow back action of the compression piston'compresses the operating spring to store sufiicient mechanical energy to accomplish feeding of projectiles and other necessary mechanical functions.

It is further contemplated that the principles of this invention can be utilized in various automatic or semiautomatic firearms in which conventional recoil-operation or 'gas-operation is utilized in conjunction with the blow-back action of the compression piston to accomplish necessary mechanical functions. i What is claimed is: r

1. In a firearm including a barrel and a trigger, a bolt operative to engage and make a fluid tight seal with respect to one end of the barrel, said bolt cooperating with a projectile disposed in the barrel to define a compression chamber, a fluid supply container communicating with the compression chamber, pump means in circuit with the container and the chamber and including a piston and a cam operatively connected to the trigger, said pump means being responsive to operation ofthe trigger eifective to meter fluid from the container to the chamber, and compression means including the bolt responsive to operation of the trigger for changing the 'volume of the chamber whereby fluid introduced therein is pressurized.

Q; Thefireann of claim 1 wherein the pump and at least two check valves are disposed between the fluid supply container and the pressure chamber, one check valve cooperating with the fluid supply container and the other check'valve cooperating with the pressure chamber.

References Cited in thefile ofthis patent UNITED STATES PATENTS 

